The goals of the Northwestern University (NU) Multidisciplinary Clinical Research Center (MCRC) are to: 1) conduct cutting-edge research aimed at the prevention or control of rheumatic diseases and poor outcomes associated with these conditions; 2) provide the academic environment that a) supports the multidisciplinary research of MCRC investigators, and b) organizes and galvanizes rheumatic disease research at NU. The current MCRC at NU operates as an integrated unit to address a broad range of clinical research endeavors. The MCRC continues to unite the NU Feinberg School of Medicine Division of Rheumatology in the Department of Medicine, the Department of Preventive Medicine, and the Institute for Healthcare Studies, as well as the NU Clinical and Translational Sciences Institute (NUCATS, NU's CTSA entity). The proposed new cycle of our MCRC illustrates the strength of these relationships and new collaboration development with the Department of Medical Social Sciences and the NU Prosthetics and Orthotics Center. As this application will show, we have an outstanding, well-organized research base as well as unique institutional resources that we incorporate and leverage. In turn, our Center continues to enrich the environment by developing new resources for our institution. The proposed new cycle of the NU MCRC includes an Administrative Core, a Methodology/Data Management Core, and 3 projects: Project 1: Physical Activity Changes & Thresholds: Quality of Life and Outcomes in Knee 0A; Project 2: Defining Targets for Therapy to Delay Cartilage Loss and Poor Outcome in Knee OA; Project 3: Evaluation of an Algorithm to Detect Rheumatoid Arthritis Cases in Cohort Studies. The specific objectives of this proposal are to: secure funding for these 2 Cores and 4 projects; to leverage this MCRC funding to further enhance rheumatic disease research at NU; and to participate in the national effort to increase awareness within the academic community and the community at large of the public health burden of the rheumatic diseases and the possible public health, medical, and rehabilitative solutions for these conditions and their consequences. We are strongly positioned to complete the work we propose and to continue to serve as an organizational and scientific focus to energize rheumatic disease research at NU.